Electromagnetic response of a single phase Y-Ba-Cu-O compound superconducting in the 90 K range

The results of x-ray diffraction, electrical resistance, DC and AC magnetization studies on two specimens of compositions Y_2.1Ba_3.9Cu₆O_14−δ and Y_1.8Ba_4.2Cu₆O_14−δ are presented. Our studies confirm that La₃Ba₃Cu₆O₁₄ type orthorhombic phase is responsible for superconductivity in the 90 K range. The heat treatment that yields high quality samples with sharp transition in electrical resistance as well as in AC magnetic susceptibility measurements is described. Magnetic response just belowT _c is found to be sensitive to the measuring field.